[Study on the epidemiological characteristics and natural infectious focus of Angiostrongylus cantonensis in Shenzhen area of Zhujiang Delta in China].

OBJECTIVE: To delimit the natural infectious focus, including the distribution of wildlife, species, ecology of intermediate hosts and final host of Angiostrongylus cantonensis, as well as the routes of transmission and epidemiological characteristics and wildlife of human Angiostrongylus cantonensis, based on human diverging cases identified in Shenzhen, southern area of China. METHODS: Data including rate of infection and density of Angiostrongylus cantonensis among different hosts in 12 different areas in Shenzhen was collected, using microscope to inspect homogenate liquids of snails. Wild mice were captured with mouse cage to examine the adult Angiostrongylus cantonensis. Using larva isolated from wild-snails-infected rats to observe the life cycle of Angiostrongylus cantonensis. RESULTS: Wild life of Angiostrongylus cantonensis existed in the southwest part of Shenzhen with its majority intermediate hosts as Achatina fulica. The overall rate of infection was 31% in wildlife and final host was found to be Rattus andersoni, Achatina fulica which were extensively distributed in the shrub region of Shenzhen because of suitable climate, humidity and vegetation for generating the life cycle of Achatina fulica. Human infected Angiostrongylus cantonensis was mainly due to eating raw snails or vegetables contaminated by larva of Angiostrongylus cantonensis. The peak of infection was seen from April to November in Shenzhen area. CONCLUSION: Wildlife of Angiostrongylus cantonensis existed in the southwest part of Shenzhen with major wildlife reservoir including fresh water snail and wild mouse. The existence of natural focus Angiostrongylus cantonensis was now recognized as an important source of human angiostrongyliasis in Shenzhen area.

[Biological effects of space flight on several opportunistic pathogenic bacteria and biodestructive fungi].

OBJECTIVE: To investigate biological effects of space flight on several conditional pathogenic bacteria and biodestructive fungi. METHOD: Several potentially pathogenic or biodegrading microorganisms, including bacteria, actinomyces and fungi, were carried on-board spacecraft for 7 d. Some of the biological characteristics were studied by using general microbial test technology after recovery. RESULT: In space condition, survival and growth rate were promoted, and soluble pigments were produced, while morphological properties were changed differently. The antibiotic-sensitivity of certain strains decreased, while most of them showed no changes. CONCLUSION: The reproduction ability and growth rate of these microorganisms are promoted after being carried into space, and morphological differentiation increase. The resistance to antibiotics is stable.